In this project, we developed the new instrument with which we measured the characteristics of the binocular stereo vision under the natural condition. In the experiment, each subject wore head mount display. We measured the detail properties of binocular stereo vison and monocular stereo vision based on the motion parallax. The modulation transfer function for binocular stereopsis was measured for a random dot stereogram of various stimulus areas and dot densities. The results showed that the threshold amplitude of the sinusoid divided by the average interval between dots is constant for each spatial frequency. Furthermore, at least three dots in one period are necessary to perceive the sinusoid and the radius of the spatial summation is about one degree. These data allow predictions to be made of the dimensions of hypercolumns and and the length of intracortical connections in the human visual cortex. We also found that the necessity condition for binocular stereo is very similar to that for monocular stereo. Therefore, these conditions reflects the property of the surface reconstruction process in the brain.